New motorized clock drive for the USNO’s Photographic Telescope

With the longer focal length of the new 10-inch lenses, with focal lengths of 133 inches, for the USNO Photographic Telescope, better guiding controls were necessary, so a new electric clock drive was built, designed by Peters and made at USNO, to replace the old weight driven conical pendulum clock drive. This allowed guiding in right ascension to be done by adjusting the speed of the motor, while the declination guiding was still controlled using the endless rope. For more information, see: Peters, G.H., 1922, The New Electric Clock Drive for the Photographic Telescope of the U.S. Naval Observatory, Popular Astronomy, Vol. XXX, No. 2, page 71.

USNOA-2021-015 USNO Glass Plate Publication Images

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